I can't find the other four spark plugs on a cadillac 2001 deville I found the first four when i removed cover up near the radiator

Ignition Coils/Modules
The electronic ignition system uses an individual ignition coil for each cylinder. There are two separate ignition module assemblies located in the camshaft cover of each cylinder bank. Each ignition module assembly contains an ignition control module and four ignition coils. Each ignition coil connects directly to a spark plug using a boot. This arrangement eliminates the need for secondary ignition wires. The ignition module assemblies receive power from a fused ignition feed. Both ignition module assemblies connect to chassis ground. A Reference Low and four ignition control (IC) circuits connect each ignition module assembly to the PCM. The PCM uses the individual IC circuits to control coil sequencing and spark timing for each ignition coil. The IC circuits transmit timing pulses from the PCM to the ignition control module to trigger the ignition coil and fire the spark plug. The PCM controls ignition system sequencing and timing events

Outside of radiator is most likely full of dirt,leaves,
bird feathers,etc.
Remove as many things as necessary, & use an air hose
followed by garden hose to clean radiator.

Could try a new thermostat & make sure spark plugs
& basic preventative maintenance is done

Change Power Steering,Trans & Motor Oils
Old fluids won't remove heat well

I believe you are correct - the radiator is probably plugged, but you should also check the water pump.

it is a northstar, so you need to remove the cop covers, egr and hoses-it is a little more involved than the front, but if you did the fronts, it is about twice as involved.

you need to remove the intake manifold cover(injector sight shield) above both valve covers to remove the spark plugs.good luck.

2001 Cadillac Deville 4.6L SFI DOHC 8cyl Removal & Installation procedure...

1. Before servicing the vehicle, refer to the Precautions section.
2. Drain the coolant.
3. Remove or disconnect the following:
Negative battery cable
Upper fill panel, if equipped
AIR injection control valve, if equipped
Air cleaner
Oil level indicator tube nut, if necessary
Water pump belt cover
Water pump drive belt
Lower radiator hose
Thermostat bypass hose from the coolant inlet housing
Water pump cover

4. Remove the water pump by rotating it clockwise using special Tool J 38816-1A (water pump remover/installer).

To install:

1. Install the water pump with a new O-ring, by turning it counterclockwise using the special tool, until it stops. Torque the water pump to 73 ft. lbs. (100 Nm).

1. 
   
   

Fig. To ensure proper operation, be sure to install a new O-ring (click for zoom)

2. Install or connect the following:
Water pump cover. Torque the bolts to 89 inch lbs. (10 Nm).
Lower radiator hose
Thermostat bypass hose to the coolant inlet housing
Water pump drive belt
Water pump belt cover
Oil level indicator tube nut, if necessary
Air cleaner
AIR injection control valve, if equipped
Upper fill panel, if equipped
Negative battery cable

3. Refill and bleed the cooling system.
4. Run the engine and check for leaks.


Hope this helps (remember to rate this comments)

With your hood open, look for several large and long (probably black) wires. Follow these (ignition) wires to your engine block. Where each wire ends you will find a spark plug.

The following 2001 Cadillac DeVille owners manual should help.

http://pdfcast.org/pdf/2001-cadillac-deville-owner-8217-s-manual

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Hello: The housing is the valve cover. The plugs can be removed by removing the ignition units from the top of the valve covers then remove the spark plugs.

There are no spark plug wires on the 2000-up Northstar engines. They use coil on plug design. First remove the engine service cover.(The Pretty plastic peice that has the Cadillac symbol on it) Then disconnect the coil connector which sits to the right of the coil and should just snap off by hand. Next If you remove the screws that holds the coil pack (8 screws) to the top of the cam covers, you will see 4 black round rubber boots that sit on top of the plugs. Pull the boots free to expose the plugs. The tops of the spark plugs sit directly underneath

The sparks plugs are located on the side of the engine,there will be spark plug wires covering them the number of spark plugs in your car depend on the size of the engine, like if you have a v8 there will be 8 of them if you have a v6 there will be six of them and so on. There are no spark plug wires on the 2000-up Northstar engines. They use coil on plug design. If you remove the screws that holds the coil pack to the top of the cam covers, you will see the tops of the spark plugs directly underneath. They are in the center of the cam covers.